Route selection method and apparatus therefor

ABSTRACT

A route connecting a point and another point on a network is derived in advance with respect to entire pairs of two points, and the route is stored with a transit point placed on the route in a memory. When a route between two points is retrieved, the route is divided by the transit point, and a route in each division is retrieved. Subsequently, plural routes of the divisions are connected and thus the route between the two points is derived.

This is a continuation of application Ser. No. 07/853,562, filed on Mar.18, 1992 now abandoned.

FIELD OF THE INVENTION AND RELATED ART STATEMENT

1. Field of the Invention

The present invention relates to a route selection method and anapparatus to select an optimum route from a plurality of routesconnecting between a starting point and a destination on a connectionnetwork such as a road network or a communication network.

2. Description of the Related Art

An example of a route selection apparatus in the prior art is shown inthe Japanese published unexamined patent application Sho 59-105113. Inthe prior art, a starting point and a destination are set in a guidancecontrol apparatus installed on a vehicle. The guidance control apparatusis provided with a device for measuring a position and a course of thevehicle, and thereby a present position and the course of the vehiclewhich is running on a road are detected. The guidance control apparatus,furthermore, comprises a map scored In a memory including information ofjunctions of roads, setting points disposed at regular intervals alongthe roads, and distances among the setting points. An optimum route fromthe starting point to the destination is derived on the basis of themap. When the vehicle has arrived at a setting point, a direction inwhich to travel thereafter is then indicated to a driver of the vehicle.The vehicle will arrive at the destination via the optimum route bydriving it in compliance with the Indication.

In the prior art, the optimum route between tile starting point anddestination is derived by tile known "Dijkstra method". According to theDijkstra method, "directed routes," on which respective directions aregiven in advance, are set among junction points of a plurality of roadsconnecting between the starting point and destination, and respectivedistances among the junction points are calculated along the directedroutes from the starting point to the destination. The route having theshortest distance is selected between the starting point and destinationas the optimum route. It is known that a search time in operation of theDijkstra method increases in proportion to a square of the number ofjunctions. Therefore, as the number of routes increase, the calculationoperation to search an optimum route also increases, and accordingly thesearch time increases very much.

Another prior art system is shown in the Japanese published unexaminedpatent application Hei 2-56591 (Tokkai 56591/1990). According this priorart system, data of a road network which is used in route selectionoperation is arranged in a "hierarchy structure". In the hierarchystructure of tile road network, a trunk line network of road is placedon an upper hierarchy, and a branch line network of road which isconnected to the trunk line network is placed on a lower hierarchy, andthereby the road network is classified into plural hierarchies.Moreover, a road network in each hierarchy is divided into a pluralityof blocks, and information of junctions, connection information withrespect to the roads among the junctions and connection information withrespect to a junction in an upper hierarchy are stored as map data atevery block of each hierarchy.

In the route selection operation of this prior art system, when a blockincluding a starting point and a block including a destination belong toan upper hierarchy, route selection operation is carried out betweenboth the blocks of the hierarchy. On the other, hand, when the startingpoint or tile destination belongs to a block of a lower hierarchy,first, a route which is connected to a block of an upper hierarchy isselected, and the route selection operation is migrated to the block ofthe upper hierarchy. When a first block including the starting point isidentical with a second block including the destination, or when thefirst block is placed adjacent to the second block on the samehierarchy, the route selection operation is completed.

In this prior art system, a block size representing a range of the blockis determined so that information included in each block is uniform.Therefore, even if a large amount of information exists owing to acomplicated road network, the calculation operation is reduced incomparison with the Dijkstra method because information processing iscarried out in each block.

Still other prior art is shown in U.S. Pat. No. 4,984,168. According tothis prior art, in order to determine a route between a starting pointand a destination within a short time, a digitally memorized road map isdivided into at least two levels of different grid density and regionalsize. A plurality of smaller subregions of fine grid density areassigned to a lower level, and one or more larger subregions of coarsergrid density are assigned to a higher level. Beginning with the lowerlevel of the road map, a possible route is searched. If the result arenegative, a transition is made to the next-higher level, until apositive result is attained. In determining an optimum route, favorableresult are obtained for all possible relationship of starting point anddestination.

For instance, when the starting point and destination are in the samepart (subregion) of a region, it is suitable for a route to bedetermined within the subregion. If that is not possible, then anattempt is made to reach the destination via an adjacent subregion.These operations are performed in the same level. If the starting pointand destination are far apart, then the major translations between thesesubregions are ascertained. In the road map, resistance values areassigned to the various roads and intersections. These resistancevalues, for instance, define a route length, a required travel time, onan average traffic density. If the resistance value is low, theapplicable road or connection is used preferentially for routedetermination. If the resistance value is high, it is not taken intoaccount unless other routes are not favorable.

Constant development in the road network increases the numbers of trunklines and branch lines connected thereto, consequently complicating theconnections among them. Accordingly, information in the road networkincreases day by day and thus the information processing operation whichis necessary to carry out route selection is Increased. Therefore, aroute selection apparatus for rapidly selecting an optimum route fromthe complicated road network has been sought.

OBJECT AND SUMMARY OF THE INVENTION

An object of the present invention is to provide a route selectionmethod and an apparatus therefor in which the information processingoperation for selecting an optimum route between a starting point and adestination reduced significantly in a connection network.

The route selection method in accordance with the present inventioncomprises the steps of:

storing data representing a route between two arbitrary points on aconnection network having a plurality of points in an interpoint routememory in advance,

designating two points in the points stored in the interpoint routememory,

deriving a route between the two points by retrieving the routecorresponding to the designated two points, and

outputting data of the route between the two points.

The route selection apparatus in accordance with the present inventioncomprises:

an interpoint route memory for storing data representing routes producedby connecting two points on a connection network having a plurality ofpoints,

point input means for designating the two points,

route retrieval means for retrieving the route between two pointsdesignated by the point input means on the basis of the routecorresponding to the two points stored in the interpoint route memory,and

output means for outputting route data retrieved by the route retrievalmeans.

While the novel features of the invention are set forth particularly inthe appended claims, the invention, both as to organization and content,will be better understood and appreciated, along with other objects andfeatures thereof, from the following detailed description taken inconjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a first embodiment of a route selectionapparatus In accordance with the present invention;

FIG. 2 is a flow chart of the operation of the first embodiment;

FIG. 3 is an example of a road map in the first embodiment;

FIG. 4 is an example of a road map in a second embodiment of the routeselection apparatus in accordance with the present invention;

FIG. 5 is a block diagram of a third embodiment of the route sectionapparatus in accordance with the present invention;

FIG. 6 is a flow chart of the third embodiment;

FIG. 7 is an example of a road map of a fourth embodiment in accordancewith the present invention;

FIG. 8 is a flow chart of the fourth embodiment;

FIGS. 9(a), 9(b), 9(c) and 9(d) represent routes in the fourthembodiment;

FIG. 10 is a block diagram of a fifth embodiment of the route selectionapparatus in accordance with the present invention;

FIG. 11 is an example of a road map in the fifth embodiment;

FIGS. 12(a) and 12(b) are flow charts of operation of the fifthembodiment;

FIG. 13 is a block diagram of a sixth embodiment of the route selectionapparatus In accordance with the present invention;

FIGS. 14(a), 14(b) and 14(c) are flow charts of operation of the sixthembodiment;

FIG. 15 is a diagram of an example of arrival ranges in the sixthembodiment.

It will be recognized that some or all of the Figures are schematicrepresentations for purposes of illustration and do not necessarilydepict the actual relative sizes or locations of the elements shown.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First embodiment!

FIG. 1 is a block diagram of a route selection apparatus of a firstembodiment In accordance with a present invention. An "interpoint routememory 101" is a memory means such as a CD-ROM which stores data ofentire routes among entire points on a road network in advance. "Pointinput means 102" is an input apparatus for designating two points (astarting point and a destination) to derive a route from among thepoints stored in the interpoint route memory 101. The point stored inthe interpoint route memory 101 is named as "route store point". Thedata of the entire routes among the route store points are stored in theinterpoint route memory 101.

"Route retrieval means 103" comprising a CPU and a memory is to retrievea route between the designated two points from among the data stored inthe interpoint route memory 101.

"Output means 104" is an output device such as a display device fordisplaying a route retrieved by the route retrieval means 103. Theoutput means 104 may be a voice outputting device for indicating theroute by voice. The output device can be constituted to indicate theroute by image or voice by combining it with a present positiondetection apparatus representing a present position of a vehicle.

The point input means 102 for designating the starting point anddestination comprises a display device for displaying a map and theroute store points in the map on the same display. An operator or adriver of the vehicle selects two points for the starting point anddestination from among the route store points displayed on the displaydevice. The designated starting point and destination are inputted tothe route retrieval means 103, and a combination of the starting pointand destination is retrieved from among combinations of two points onthe network stored in the interpoint route memory 101, and thus a routecorresponding to the combination is read out. The route data is outputto the output means 104.

Operation of the route selection method In the first embodiment is shownIn a flow chart of FIG. 2. A starting point and a destination to derivea route are selected from among the route store points and aredesignated at step 201. At the step 201, the route between thedesignated two points is retrieved from among the data stored routesamong entire points, and a retrieved route is output at step 203.

Detailed operation of the first embodiment is elucidated by using anexample hereafter. FIG. 3 is a diagram of a road network representingroutes connecting among five points 1, 2, 3, 4 and 5. Entire routesconnecting are produced by connecting among the five points arepredetermined by designating one of five points as a starting point andthe other thereof as a destination, and the data of the entire routesare stored in the interpoint route memory 101 as "interpoint routedata". An example of the interpoint route data is shown in Table 1.

                  TABLE 1    ______________________________________    Interpoint route data    Combination of points    Starting point Destination                             Transit point    ______________________________________    1              2         --    1              3         --    1              4         2    1              5         3    2              1         --    2              3         --    2              4         --    2              5         4    3              1         --    3              2         --    .              .         .    .              .         .    .              .         .    5              2         4    5              3         --    5              4         --    ______________________________________

In Table 1, combinations of two points selected from five points areshown in a comprehensive column of "combination of points", for example.Numerals in the heft column thereof represent starting points andnumerals in the right column represent destinations (the numerals in theright column are allowed to be the starting points and the numerals Inthe left column are allowed to be the destinations). Numerals in thecolumn of "transit points" represent a transit point between two pointsshown on the same row in the comprehensive column of the combination ofpoints. The combination of points having no transit point is representedby "-". The transit points is one of the route store point.

In the first embodiment, as shown in the Table 1, a route which isformed by a combination between two arbitrary points is stored withrespect to entire combinations of the points on the network and onepoint on the respective routes is also stored. When the point 1 is astarting point and a point S is a destination, for example, thecombination of these two points 1 and 5 is retrieved in the column ofthe combination of the points, and a route transit point correspondingto the combination of these two points 1 and 5 is retrieved in thecolumn of the transit point of the Table 1. In the above-mentionedexample, a point 3 is retrieved in the column of the route transit pointof the Table 1. Consequently, the route from the point 1 to the point 5is determined as "point 1 → point 3→ point 5".

In the storing operation of the routes among entire points on thenetwork, the routes which are predetermined by the Dijkstra method orthe like using the road network can be stored therein. The road networkdata includes data of positions of points and connection relations amongthese points. Moreover the routes may be derived by hand on the basis ofan ordinary human sense.

In the first embodiment, the route between two points is obtained bycombination of plural transit points. Combination of the route transitpoints with respect to combination of the two points is shown in Table2.

                  TABLE 2    ______________________________________    Combination of points                  Combination of route transit points    ______________________________________    1-5           2          3        4    1-4           2          3    1-3           2    ______________________________________

As shown in Table 2, For example, three route transit points 2, 3 and 4need to be stored with respect to the route between the points 1 and 5.Therefore, the data of the transit points rapidly increase in accordancewith increase of the number of point. For this reason, the routeselection apparatus in the first embodiment is suitable for the roadnetwork having relatively small number of points.

Second embodiment!

The second embodiment of the route selection method and apparatus isdirected to greatly reduce the data of routes to be stored in theinterpoint route memory 101 in comparison with the first embodiment.Hardware structure in the second embodiment is substantially identicalwith that of the first embodiment. In the second embodiment, at leastone point on the way of a route is stored in the interpoint route memory101, as a "transit point". The data of the transit point is included inthe data of the routes among points on the road network. And when aroute between designated two points is derived, the route is dividedinto plural sub-routes by putting the transit point on the way of theroute as a boundary point. Then a further transit point is determinedbetween the designated point and the boundary point.

FIG. 4 is an example of a road map of a route including five points 1,2, 3, 4 and 5. A combination of points (the point 1 is a starting point)and transit point (corresponding) to the combination are predeterminedas shown in Table 3.

                  TABLE 3    ______________________________________    Combination of points                     Transit point    ______________________________________    1-5              4    1-4              3    1-3              2    1-2    ______________________________________

The data shown in the Table 3 are stored in the interpoint route memory101.

Retrieval operation of a route in the second embodiment is elucidatedhereafter. After the two points (starting point and destination) toderive a route are designated, in the route retrieval means 103, thecombination of the two points is retrieved from combinations among theentire points on the network stored in the interpoint route memory 101.Then a first transit point corresponding to the combination of the twopoints is read out. Subsequently, a combination of the starting pointand the first transit point is retrieved, and hence a second transitpoint corresponding to the combination of the starting point and thefirst transit point is read out. In the same way, a third transit pointcorresponding to the combination of the starting point and the secondtransit point is read out. Furthermore, a fourth transit point isretrieved based on the combination of the destination and the firsttransit point, and a fifth transit point is also retrieved based on thecombination or the first and second transit points.

As mentioned above, according to the second embodiment, the respectivetransit points corresponding to the combination of the starting pointand a transit point, a combination of two transit points and thecombination of the transit point and the destination are stored in theinterpoint route memory 101. And points on the route between thestarting point and the destination are determined by retrieving them Inthe interpoint route memory 101 by the route retrieval means 103.Consequently, the route between the starting point and the destinationis determined by a chain of a plurality of transit points, the startingpoint → first transit point → a second transit point → a third transitpoint . . . the destination. The derived route is output from the outputmeans 104.

An example of route retrieval operation is shown in Table 4. In theTable 4, for the sake of simplicity, the point 1 of five points 1, 2, 3,4 and 5 is designated as the starting point, and the point 5 isdesignated as the destination. In the example, a point located adjacentto the destination between the starting point and destination isselected for a transit point.

                  TABLE 4    ______________________________________    Combination              Chain of transit    of points     Transit point                             points    ______________________________________    Step 1          1-5         4          1            4    5    Step 2          1-4         3          1        3   4    5    Step 3          1-3         2          1   2    3   4    5    Step 4          1-2         --         1   2    3   4    5    ______________________________________

In order to derive a route from the starting point to the destination,first, combination of the point 1 and the point 5 is retrieved(hereinafter, a route from the point 1 to the point 5 is represented by"combination 1-5"), and a transit point 4 corresponding to thecombination 1-5 is derived at step 1 of the Table 4. Subsequently, atstep 2, combination 1-4 is retrieved and a resultant transit point 3 isderived. In a similar manner at step 3, combination 1-3 is retrieved,and a resultant transit polar 2 is derived. Finally at step 4,combination 1-2 is retrieved. If no transit point is stored with respectto the combination 1-2, the route between the points 1 and 5 isrepresented by a chain of the transit points 4, 3 and 2. "Chain oftransit point" in the right column of Table 4 represents route derivedin each step.

According to the second embodiment, in order to select a route betweentwo points, only one point on the way of a route is stored in theinterpoint route memory 101 in advance. Therefore, data for storing theroute is greatly reduced in comparison with the first embodiment.

In the example shown in the Table 3, a point located adjacent to thedestination is selected for a transit point, but a point locatedadjacent to the starting point can be selected for a transit point. Inthis case, a chain of the transit points is derived in the orderdirected from the starting point to the destination.

Third embodiment!

In the case that two points to derive a route are minor points which arenot stored in the Interpoint route memory 101, the route can be derivedby storing such points in a map data memory 501 in the third embodimentSee FIG. 5. In the map memory 501, connection relations (which isrepresented by a route store point) between neighboring two points inthe minor points are stored in addition to the connection relationsbetween neighboring two points in the points stored in the interpointroute memory 101. Routes among more points than that in the firstembodiment can be derived by combining data of the map data memory 510with the data of the Interpoint route memory 101.

FIG. 5 is a block diagram of a route selection apparatus in the thirdembodiment of the present invention. The interpoint route memory 101,point input means 102, route retrieval means 103 and output means 104have the same configuration and function as those of the firstembodiment.

The map data memory 501 stores the route store points stored in theinterpoint route memory 101 and the route store points of minor pointswhich are not stored in the interpoint route memory 101. The map datamemory 501 further stores road information such as connection betweenthe minor point and the point stored In the interpoint route memory, anddata of travel times for traveling the routes.

Search means 502 comprises a CPU and a memory, and searches a route froma "starting point" to a "route store point adjacent to the startingpoint" which defined as a route store point that is located adjacent tothe starting point, and a route from a destination to a "route storepoint adjacent to the destination" by using network data read out fromthe map data memory 501. Then the route between both the route storepoints is retrieved by the route retrieval means 103. The route from thestarting point to the route store point adjacent to the starting pointand the route from the destination to the route store point adjacent tothe destination and the route between both the route store points areconnected by route constitution means 503. Consequently, the route fromthe starting point to the destination is derived.

An outline of the operation in the block diagram shown in FIG. 5 iselucidated hereafter. Network data in the map data memory 501 is readout by the point input means 102, and an operator designates using thepoint input means 102 two points to derive a route on the network.

In the search means 502, the network data representing the neighborhoodof the starting point is read out from the map data memory 501 incorrespondence to the designated starting point, and a first route fromthe starting point to a route store point adjacent to the starting pointis searched by the Dijkstra method, for example. In the above-mentionedsearch operation, if the operator intends to seek a route having ashortest travel time, such order can be inputted to the point inputmeans 102. A second route from the destination to a route store pointadjacent to the destination is searched by using the network datarepresenting the neighborhood of the destination.

The data of the first route between the destination and the route storepoint adjacent to the starting point and the data of the second routebetween the destination and the route store point adjacent to thedestination are inputted to the route constitution means 503. Then, inthe route retrieval means 103, a third route between the route storepoint adjacent to the starting point and the route store point adjacentto the destination is retrieved from the data stored in the interpointroute memory 101 on the basis of the combination of the route storepoint adjacent to the starting point and the route store point adjacentto the destination which are inputted from the route constitution means503. And thus the third route is derived in a similar manner shown inthe first and second embodiments.

Subsequently, in the route constitution means 503, the first route,second route and third route are connected into one route in the namedorder, and the route from the starting point to the destination iscompleted. The completed route is output from the output means 104.

FIG. 6 is a flow chart of operation of the route relation method In thethird embodiment. First, two points (starting point and destination) toderive a route are designated at step 601 (operation in the point inputmeans 102). At step 602, a first route from the starting point to theroute store point adjacent to the starting point and the second routefrom the destination to the route store point adjacent to thedestination are searched, and the route store point adjacent to thestarting point having the first route to the starting point isdetermined, and the route store point adjacent to the destination havingthe second route to the destination is also determined (operation of thesearch means).

At step 603, the third route between the route store point adjacent tothe starting point and the route store point adjacent to the destinationis retrieved in the data of the route stored in the interpoint routememory 101 (operation of the route retrieval means 103). The retrievalis carried out based on the combination of the first route store pointand the second route store point determined at step 602. At step 604,three routes of the first, second and third routes are connected to oneroute, and the route from the starting point to the destination isderived (operation or the route constitution means 503). Finally thederived route is output at step 605 (operation of the output means 104).

Hereafter, detailed operation of the route selection apparatus of thethird embodiment is elucidated by using a road map shown in FIG. 7.Referring to FIG. 7, a point 701 is the starting point, a point 702 isthe destination, a point 703 is the route store point adjacent to thestarting point. First, a route 704 between the point 701 and the point703 is searched from the starting point (point 701) to the route storepoint adjacent to the starting point (point 703) on the basis of thenetwork data stored in the map data memory 501. Subsequently, a point705 is the route store point adjacent to the destination, and a route706 between the destination (point 702) and the route store pointadjacent to the destination (point 705) is searched on the basis of themap data stored In the map data memory 501. Finally, a route 707 betweenthe points 703 and 705 is retrieved in the interpoint route memory 101as a route corresponding to combination of the point 703 and point 705.

After the starting point (point 701) and the destination (point 702) hasbeen set first, the network data in the neighborhood of the startingpoint (point 701) is read out, and a point which is connected to thepoint 701 on the network is searched from the starting point of thepoint 701 toward the point 702. For example, in order to derive a routehaving the shortest travel time, a route store point which can bearrived from the point 701 with the shortest travel time have beensearched on the network, and a route store point 703 is selected for theroute store point adjacent to the starting point. The derived route 704between the point 701 and the point 703 is stored in the search means502.

In a similar manner, network data of the map in the neighborhood thedestination (point 702) is read out, and a point which is connected tothe point 702 on the network of the map is searched from the point 702toward the point 701. When a route store point having the shortesttravel time is derived on the network, the route store point is selectedfor a route store point (point 705) adjacent to the destination, and aroute 706 is derived. The derived route 706 is stored in the searchmeans 502. Then a route between the points 703 and 705 is retrieved inthe interpoint route memory 101, and the route 707 stored correspondingto the combination of the points 703 and 705 is derived. Finally, threeroutes 704, 707 and 706 are connected to one route in the named order,and thus the route from the starting point (point 701) to thedestination (point 702) is determined.

As mentioned above, according to the third embodiment, since the mapdata memory 501 is provided, even If a point which is not included inthe route store points stored in the interpoint route memory 101 isselected for a starting point or a destination, a route from thestarting point to a route store point can be derived by searching It inthe map data memory 501. Therefore, the number of point to be designatedto derive a route greatly increases in comparison with those of thefirst and second embodiments.

In the above description of the third embodiment, though a shortesttravel time is a criterion in selection of a route, the criterion may bea distance between the starting point and the destination. Moreover,selection of a route which is easy to run may be the criterion asreplacement for the shortest travel time or the distance. Information of"one way traffic" or information for "prohibiting approach" may be addedto data of the connection relation, and a route including theseInformation can be derived.

Fourth embodiment!

The fourth embodiment is directed to provide the route selection methodand apparatus by which an operator can select a desirable route fromplural routes on the basis of an advantageous evaluation value such as ashortest travel time. The block diagram of the route selection apparatusin the fourth embodiment is identical with that of the third embodimentas shown in FIG. 5. The map data memory 501, the point input means 102and the output means 104 are identical with those of the thirdembodiment in configuration and operation. The interpoint route memory104 in the fourth embodiment stores routes corresponding to combinationsof two points and travel times or distances between these two points. Inthe search means 502, plural routes from a starting point to at leasttwo route store points adjacent to the starting point are searched, andplural routes from a destination to at least two route store pointsadjacent to the destination are also searched. The searched routes areapplied to the route constitution means 503.

Then, routes of entire combinations among plural route store pointsadjacent to the starting point and plural route store points adjacent tothe destination are retrieved by the route retrieval means 103 on thebasis of the searched routes, and plural routes from the starting pointto the destination are selected from routes searched by the search means502 and are stored therein. In the route retrieval means 103, a route onthe basis of a travel time or a distance between two points inputtedfrom the route constitution means 503 is retrieved in the interpointroute memory 101.

Subsequently, an outline of operation in the fourth embodiment to derivea route laving a shortest travel time is elucidated hereafter. First,two points (starting point and destination) designated by the operatoron a road network are set with the point input means 102. In the searchmeans 502, the network data in the neighborhood of the starting pointare read out from the map data memory 501 in correspondence to thestarting point, and a predetermined number of route from the startingpoint to the predetermined number of the route store points adjacent tothe starting point are searched.

In a similar manner, a predetermined number of route from thedestination to the predetermined number of route store points adjacentto the destination are also searched. The data of the routes among thestarting point and the plural route store points adjacent to thestarting point and the routes among the destination and the plural routestore points adjacent to the destination are inputted to the routeconstitution means 503. Then the respective travel times of routes amongthe plural route store points adjacent to the starting point and theplural route store points adjacent to the destination are derived by theroute retrieval means 103.

FIG. 8 is a flow chart of the outline of the operation of the routeselection method In the fourth embodiment. First, at step 801, twopoints to derive a route are selected from the points on the network(operation of the point input means 102). Second, at step 802, routesfrom the starting point to plural route store points adjacent to thestarting point are searched by using the road network data in theneighborhood of the starting point. At step 803, routes from thedestination to plural route store points adjacent to the destination aresearched by using the network data in the neighborhood of thedestination (operation of the search means 502).

At step 804, entire routes formed by combinations from among the routestore points adjacent to the starting point and the route store pointsadjacent to the destination are retrieved (route retrieval means 103).Then at step 805, plural routes from the starting point to thedestination are derived from the routes searched at the steps 802 and803 and the routes retrieved at the step 804 (operation of routeconstitution means 503). Finally, the derived routes are output at step806 (operation of the output means 104).

FIGS. 9(a), 9(b), 9(c) and 9(d) are diagrams of routes between astarting polar 901 and a destination 904. Detailed operation of theroute selection apparatus in the fourth embodiment is elucidatedhereafter. Referring to FIG. 9(a), four route store points 902 adjacentto the starting point 901 are selected in the neighborhood of thestarting point 901. The range of the neighborhood of the starting point901 is shown by a circle 903, and search of the route store points arecarried out in the range of the circle 903. In a similar manner, fourroute store points 905 adjacent to the destination 904 are selected inthe range of a circle 906. The search of the route store points iscarried out In the range of the circle 906 by using the road networkdata. In search operation, the range to be searched is enlarged so thata predetermined number of the route store point (for example four in theabove-mentioned cases) can be derived by searching routes from thestarting polar 901 to a route store polar 902. These route store points902 adjacent to the starting point searched as mentioned above, arestored in the search means 502. In a similar manner, the range to besearched and the route store points 905 adjacent to the destination 904are derived.

Subsequently, plural routes among the route store points 902 adjacent tothe starting point 901, and the route store points 905 adjacent to thedestination 904 are retrieved by the route retrieval means 103 as shownin FIG. 9(b). Referring to FIG. 9(b), four route store points 902 arecombined with the four route store points 905, and entire combinationsamong them are retrieved by the route retrieval means 103. Consequently,sixteen routes 908 are derived among the four route store points 902 andthe four route store points 905.

Then, suitable routes from the starting point 901 to the route storepoints 905 adjacent to the destination 904 are selected from the sixteenroutes 908 retrieved by the route retrieval means 103 as shown in FIG.9(c). Referring to FIG. 9(c), four routes are selected by connection ofroutes 909 and 908 for the suitable routes from the starting point 901to the ,route store points 905 adjacent to the destination 904, forexample.

Finally, routes 910 from the destination 904 to the four route storepoints 905 are derived as shown in FIG. 9(d). Consequently, four routesfrom the starting point 901 to the destination 904 are decided as"starting point 901 → two route store points 902 → four route storepoints 905 → destination 904".

According to the fourth embodiment, since plural routes between thestarting point and destination are derived and are shown to theoperator, the operator can select an optimum route in compliance withhis choice. In the above-mentioned operation, search in the neighborhoodof the destination can be carried out before search in the neighborhoodof the starting point. Moreover, routes from plural route store pointsadjacent to the starting point to the destination can be derived inadvance, and thereafter plural routes from the starting point to therespective route store points adjacent to the starting point can bederived. If necessary, an optimum route can be selected from the pluralroutes decided in the fourth embodiment on the basis of an advantageousevaluation value such as a total travel time or a total distance betweenthe starting point and destination.

Fifth embodiment!

FIG. 10 is a block diagram of the route selection apparatus in the fifthembodiment. Referring to FIG. 10, the point input means 102 and outputmeans 104 are identical with those of the first embodiment inconfiguration and function, and therefore the redundant descriptionsthereon are omitted. In the fifth embodiment, a traffic network such asa road network is classified into plural hierarchies. For example, amajor trunk line such as a highway is classified into an upper hierarchyand a minor branch line or a lane is classified into an lower hierarchy.The data of a point has a "hierarchy identifier" which indicates ahierarchy of the point on the traffic network. The data of the pointhaving the hierarchy identifier and connection data between points arestored in the interpoint route memory 1004 shown in FIG. 10.

FIG. 11 shows hierarchy maps "a", "b" and "c" on which points on thetraffic network of a map M are classified into three hierarchies A, Band C, respectively. A criterion of classification is a width of a roadat a point, for example. Three kinds of roads which are classified onthe basis of the road width are shown on the map M shown in FIG. 11. Thewidest road A1 (hereinafter is referred to as trunk line) belongs to thehierarchy A as shown in the hierarchy map "a". Middle width roads B1belong to the hierarchy B and lanes C1 belong to the hierarchy C. On thehierarchy maps "a", "b" and "c", the points 1100, 1101, 1110, 1111 and1112 belong to the hierarchy A and are shown in the hierarchy map "a".The points 1120, 1125, 1151, 1152 . . , for example, belong to thehierarchy B, and the points of the hierarchies A and B are arranged onthe hierarchy map "b". Point 1108 and 1150 . . . , for example, belongto the hierarchy C and are arranged on the hierarchy map "c". Entirepoints of the map M are shown in the hierarchy map "c". An example ofdata stored in the interpoint route memory 1104 is shown in Table 5.

                  TABLE 5    ______________________________________    Reference point    number    Hierarchy  Joining point                                    Route number    ______________________________________    1101      A          1110       A1    1101      B          1102       B1    1101      B          1103       B2    1101      B          1104       B3    1101      B          1105       B4    .         .          .          .    .         .          .          .    .         .          .          .    1102      B          1104       B100    .         .          .          .    .         .          .          .    .         .          .          .    1106      B          1101       B200    1106      B          1102       B201    .         .          .          .    .         .          .          .    .         .          .          .    1106      C          1107       C1    1106      C          1108       C2    .         .          .          .    .         .          .          .    .         .          .          .    ______________________________________

Referring to Table 5, a "reference point number" represents a "referencepoint" on the map M. The reference point serves as a reference inretrieval operation of a route, and a point on the map M is used for thereference point when it Is necessary. The reference point is one pointof the route store points. A "hierarchy" shows a hierarchy in which areference point belongs. A "joining point" is a point to which areference point having a reference point number Is connected. A "routenumber" represents a route between a reference point and a joiningpoint. Arrangement of the data of the "reference point number","hierarchy", "joining point" and "route number" can be made in variousmanners to realize high speed retrieval. For example the data can bearranged in the Table 5 in the order of the hierarchies or the referencepoint number. Moreover, in order to reduce the data, as mentioned in thesecond embodiment, at least one transit point on the way of a route canbe stored.

An "object point" is one of the route store points and defined as apoint which is similar to the reference point, The object point islocated adjacent to a destination and serves as a point in retrievaloperation by which a route is retrieved "from the destination to astarting point".

In the interpoint route memory 1004, entire routes among the pointswhich belong to the respective hierarchies are not stored therein, forrestrictive purpose of a data size, a predetermined number of routes(10-100, for example) located adjacent to a point are stored. The numberof stored route is "ten" in the fifth embodiment, for example.

Detailed operation of the route selection apparatus in the fifthembodiment is elucidated with reference to FIG. 11 hereafter.

First, a starting point 1108 and a destination 1150 are designated inthe map M shown In FIG. 11, for example. Second, a "reference point" toretrieve a route to the destination Is set on the starting point 1108,and an "object point" to retrieve a route to the starting point is seton the destination 1150. Namely, the starting point 1108 is temporarilyused for the reference point and the destination 1150 is also used forthe object point in an initial state. In general, the object point islocated adjacent to the destination 1150 and a point is used for theobject point when It is necessary. Subsequently, route retrievaloperation is carried out on the lowest hierarchy C. In the embodiment,since the number of stored routes is restricted to ten, there is nooccasion where a route connecting between the starting point 1108 anddestination 1150 is retrieved by retrieving ten routes adjacent to thestarting point 1108. In the above-mentioned case, therefore retrievaloperation is tried on the next upper hierarchy B.

Prior to the retrieval on the next upper hierarchy a "new referencepoint" and a "new object point" have to be set on the hierarchy B.First, since the reference point on the starting point 1108 exists onlyon the hierarchy map "c", a point 1106 which exists on the next upperhierarchy B and is at the Immediately adjacent position to the startingpoint 1108 is selected for the "new reference point" on a route C1including both the points 1108 and 1106. At this time, the route C1between the old reference point (starting point 1108) and the newreference point 1106 is stored In the route retrieval means 1103. In asimilar manner, since the object point on the destination 1150 existsonly on the hierarchy map "c", a point 1151 which exists on the nextupper hierarchy B and is at the Immediately adjacent position to thedestination 1150 is selected for the new object point. At this time, theroute C10 between the old object point (destination 1150) and the newobject point 1151 is stored in the route retrieval means 1103.Consequently, since the new reference point 1106 and new object point1151 are set on the hierarchy B, route retrieval operation is carriedout on the hierarchy B. In the event that the data of a route connectingbetween the new reference point 1106 and new object point 1151 does notexist on the hierarchy B because of restriction of the number of storedroutes, the retrieval operation must be tried on an upper hierarchy,hierarchy A.

For preparation of retrieval operation on the hierarchy A, a further newreference point and a further new object point are selected. A point1101 which is at the immediately adjacent to the reference point 1106 onthe hierarchy A is selected for the further new reference point, and apoint 1110 which is at the immediately adjacent to the object point 1151on the hierarchy A is selected for the further new object point. The newreference point 1101 and new reference point 1110 are set on thehierarchy A, and route retrieval operation is carried out on thehierarchy A. Consequently, a route A1 is retrieved between the newreference point 1101 and the new object point 1110. Thus, five routes ofa first route C1 from the starting point 1108 to the reference point1106 on the hierarchy B, a second route B1 from the reference point 1106to the reference point 1101 on the hierarchy A, a third route A1 fromthe reference point 1101 to the object point 1110 on the hierarchy A, afourth route B10 from the object point 1110 to the object point 1151 onthe hierarchy B and a fifth route C10 from the object point 1151 to thedestination 1150 on the hierarchy C are retrieved, and the route betweenthe starting point 1108 and the destination 1150 is determined byconnecting these five routes.

FIGS. 12(a) and 12(b) are flow charts of operation in the fifthembodiment. At step 1301, the starting point 1108 and destination 1150are selected from the route store points stored In the Interpoint routememory 1004, and are designated with the point input means 102.Subsequently at step 1302, an Investigation hierarchy to be searched isset to the lowest hierarchy (hierarchy C in the embodiment), and thereference point is set to the starting point 1108, and the object pointis see to the destination 1150. At step 1303, a route from the referencepoint to a connecting point from the reference point is retrieved in thehierarchy C, and the data of the route is read.

Subsequently, at decision step 1309 if there is a route between thereference point and the object point, the flow advances to step 1310,and the route number of the route is recorded. If there is no routetherebetween, the flow advances to step 1304, and the investigationhierarchy is changed to the next higher hierarchy (hierarchy B). Then,at decision step 1305, if the reference point is not found on thehierarchy B, a point which is connected to the reference point (startingpoint) and exists on the hierarchy B is retrieved, and the point is setto the new reference point at step 1306. And the route from the startingpoint 1108 to the new reference point is stored. If the reference point(starting point 1108) exists on the hierarchy B, the flow advances fromthe step 1305 to step 1307. At decision step 1307, the object point(destination 1150) is searched in the investigation hierarchy B. If theobject point (destination 1150) exists in the hierarchy B, the objectpoint is maintained to be set on the destination 1150 as set in step1302, and the flow advances to step 1303. If the object point(destination 1150) does not exist on the hierarchy B, the flow advancesto step 1308 in a similar manner at step 1306. Then a polar which isconnected to the object point (destination 1150) and exist on theinvestigation hierarchy (hierarchy B) is selected for a new objectpoint, and the route from the destination 1150 to the new object pointis stored.

After the new reference point and new object point are set on thehierarchy B, the flow advances to step 1303, and the data of a routebetween the new reference point and new object polar are read out. Thena route corresponding to combination of the new reference point and newobject point is retrieved from the data on the hierarchy B shown inTable 5 at decision step 1309. When the route exists, the flow advancesto step 1310 and the route is recorded. If the route does not exist, theflow advances to step 1304, and Investigation hierarchy is changed tothe next higher hierarchy (hierarchy A).

Subsequently, in a similar manner to the operation on the hierarchy B,the flow advances to steps 1305, 1306, 1307 and 1308 in the named order,and further new reference polar (hereinafter is referred to as referencepoint on hierarchy A) and further new object point (hereinafter isreferred to as object point on hierarchy A) are set on the hierarchy A.

Then a route between the reference point on the hierarchy A and theobject point on the hierarchy A is retrieved on the hierarchy A at steps1303 and 1309. Since the hierarchy A is of the highest hierarchy, aroute between the reference point on the hierarchy A and the objectpoint on the hierarchy A is derived without fall. The derived route(route number) is recorded at step 1310.

Subsequently, at step 1311, the route from the starting point 1108 tothe reference point on the hierarchy A is recorded, and at step 1312,the route from the destination 1150 to the object point on the hierarchyA is also recorded. Finally, at step 1313, the routes C1. B1 from thestarting point 1108 to the reference point on the hierarchy A, the routeA1 from the reference point on the hierarchy A to the object point onthe hierarchy A and the routes B10, C10 from the object point on thehierarchy A to the destination 1150 are connected to one route in thenamed order, and the route between the starting point and destination isoutput.

According to the fifth embodiment, retrieval speed is greatly increased,since the data of the routes are stored in the respective hierarchies onthe basis of the hierarchy identifier attached to the point, andretrieval of a route is carried out on each hierarchy. Moreover, sincethe number of stored route with respect to each point is restricted to apredetermined number (ten in the example elucidated above), It is notnecessary to store a lot of data in the interpoint route memory 1004,and thus memory capacity thereof can be reduced.

In the above-mentioned example, plural reference points or plural objectpoints can be set on every hierarchies. In such case route retrievaloperation can be carried out among the plural reference points and theplural object points In a similar manner described In the fourthembodiment.

In the fifth embodiment, the number of hierarchy is not limited to threehierarchies. The criterion in classification or the hierarchy may beroad condition to drive, a gradient of the road, a toll of road, numberof pedestrian on the road side, architectures located along the road(residence area, an industrial area, or a busy shopping area). It isrecommendable that a preferable number of hierarchy may be set incorrespondence to the road condition in advance, and route retrieval iscarried out on a network having the number of hierarchies correspondingto a selected starting point and a destination.

A range of a hierarchy is decided corresponding to a capacity of amemory medium such as a CD-ROM, and a hierarchy having the most detaileddata is preferably located on the lowest hierarchy.

Sixth embodiment!

FIG. 13 is a block diagram of the route selection apparatus in the sixthembodiment. Referring to FIG. 13, the point input means 102, hierarchysetting means 1002, route retrieval means 1003, interpoint route memory1004, route constitution means 1005 and output means 104 are identicalwith those of FIG. 10 in configuration and function, and thereforeredundant descriptions thereon are omitted. In the sixth embodiment,points and routes on a road network are made to form a hierarchystructure in a similar manner in the fifth embodiment. In eachhierarchy, the number of stored route with respect to a point isrestricted to a predetermined number.

Search of a route on a lowest hierarchy having the most detailedinformation of road data is carried out in a detailed route search means1402. Detailed road network data which is searched with the detailedroute search means 1402 is stored in a map data memory 1422. Data of aresidential district map and a detailed road map may be stored Inadvance in the map data memory 1422. Furthermore, a road network may bestored in the map data memory 1422 during driving a vehicle.

A "migration point" is a point on a road network, and a route isconnected from a point on a hierarchy to a point on other hierarchythrough the migration point. The migration polar is set In a migrationpoint setting means 1403. The migration polar comprises a "forwardmigration point" and a "backward migration point". The forward migrationpoint is a migration polar on a route getting toward a destination froma starting point, and the backward migration point is a migration pointon a route getting toward the starting point from the destination. Apredetermined number of points are stored in a forward migration pointmemory 1423, through which a route migrates from a reference point on ahierarchy to other hierarchy in the direction toward the destinationfrom the starting point. In a similar manner, a predetermined number ofpoints are stored in a backward migration point memory 1424, throughwhich a route migrates from an object point on a hierarchy to otherhierarchy in the direction toward the starting point from thedestination. An example of data structure of the migration points isshown in Table 6.

                  TABLE 6    ______________________________________    Data structure of migration points                      Hierarchy                      to which    Point             migration  Migration points    number  Hierarchy is allowed (four and below)    ______________________________________    1107    C         B          1105, 1106, 1104, 1103    1107    C         A          1101,    1105    B         A          1101,    ______________________________________

Referring to Table 6, a "point number" is attached to a point positionedon a "hierarchy" listed on the same row as the point number, and a routefor connecting the point is permitted to migrate to a hierarchy listedin a box as "hierarchy to which migration is allowed". "Migration point"such as 110S, 1106, 1104 and 1103 of a predetermined number (four pointsat most in the embodiment) are stored with respect to a point having thepoint number of 1107, and the route is permitted to migrate from ahierarchy to other hierarchy only through the migration points. Even ifthe number of migration point is much more than four, four migrationpoints which are located adjacent to the point are selected in the orderof shorter distance. These selected migration points are stored in theforward migration point memory 1423 or the backward migration pointmemory 1424 in advance.

In an arrival range data memory 1425, data of an "arrival range" of aroute is stored. The arrival range is defined by a distance in which apoint has routes to other points on the same hierarchy. In other words,the route is permitted to arrive from the point to other point withinthe arrival range on the same hierarchy. An example of the arrival rangeis shown in FIG. 15. Referring to FIG. 15, a circle R1 shows a firstarrival range on the lowest hierarchy including a starting point 100 anda migration point 100A. Circles R2 and R3 show a second arrival rangeand a third arrival range on upper hierarchies, respectively. Migrationpoints 100B and 100C are included within the respective arrival rangesshown by the circles R2 and R3. Outward of the circle R3 shows anarrival range on the highest hierarchy. In general, the higher thehierarchy becomes, the wider the arrival range becomes.

Operation of the route selection apparatus in the sixth embodiment iselucidated with reference to flow charts shown in FIGS. 14(a), 14(b) and14(c). First, a starting point and a destination are inputted at step501. Second, traffic network data is read out from the traffic networkdata memory 1422 at step 1502. Then, at step 1508, plural routes fromthe starting point to route store points stored in the interpoint routememory 1004 are searched with the detailed route search means 1402. Atstep 1504, plural routes from the destination to route stored pointsstored in the interpoint route memory 1004 are also searched with thedetailed route search means 402. At step 1505. entire forward migrationpoints with respect to the route store points searched at step 1503 areread out from the forward migration point memory 1423, and referencepoints located adjacent to the starting point are selected to retrieveroutes from the starting point by using the forward migration points. Inselection of the reference points located adjacent to the startingpoint, a predetermined number of the reference point are selected fromevery hierarchies.

At step 1507, entire backward migration points to derive an object pointwhich is used to retrieve a route from the destination are read out fromthe backward migration point memory 1424. Subsequently, at step 1508, apredetermined number of object point located adjacent to the destinationare selected from the backward migration points read out at step 1507 onevery hierarchies. As mentioned above, after the predetermined number ofreference points and object points are decided on the respectivehierarchies, the investigation hierarchy for investigating a route isset to the lowest hierarchy at step 1601. Then the flow advances todecision step 1602 where it is determined if an object point exists inthe arrival range of a reference point in the investigation hierarchy.If it is, the flow advances to seep 1603 an object point does not existin the arrival range, the flow advances to step 1604, and the hierarchyto be investigated is changed to the next upper hierarchy and the flowreturns to step 1602.

In the sixth embodiment, migration of a route from a hierarchy to otherhierarchy is carried out via a migration point. A migration point oneach hierarchy is read out from the forward migration point memory 1424with respect to the predetermined number of stored points (referencepoint) which are searched with respect to a starting point. In a similarmanner, a migration point on each hierarchy is read out from thebackward migration point memory 1424 with respect to the predeterminednumber of stored points (object point) which are searched with respectto the destination. In the event that the object point is included inthe arrival range of the reference point, entire routes connected toeach reference point on the investigation hierarchy are read out at step1603.

Subsequently, at decision step 1605, It is examined whether the objectpoint is included in the connecting points of a route on theinvestigation hierarchy. If the object point is included in theconnecting points, the flow advances to step 1606; and if it is not, theflow advances to step 1606; and if step 1606, a sum of evaluation valuesis examined. The evaluation value is a value representing acharacteristic of a route between the starting point and destination.Examples of the evaluation value are "average traveling time",'distance" and "traffic congestion" or the like. When the traveling timeis employed as the evaluation value, the sum of traveling times ofplural routes connecting between the starting point and destinationbecomes the sum of the evaluation values. In the case that plural routesexist between the starting point and destination, the respectiveevaluation values of the routes are compared with each other, and theroute having the smallest evaluation value is selected for an optimumroute. When the route having the minimum evaluation value has beendetermined, the flow advances to step 1607, and the data of theInvestigation hierarchy, reference point and object point are stored.Then at decision step 1608, it is examined whether entire referencepoints on the investigation hierarchy are investigated. When theinvestigation with respect to entire reference points has beencompleted, the flow advances to step 1609, and it is examined whether anobject point is included in the reference points. If the object point isincluded in the reference points, the flow advances to step 1701, and aroute from the starting point and to the reference point is produced. Onthe contrary, if the object point is not included in the referencepoints at step 1609, the flow returns to step 1604, and theinvestigation hierarchy is changed to the next upper hierarchy. Thenoperation from step 1602 to step 1609 is repeated.

Subsequently, at step 1702, a route between the reference point andobject point is produced on the investigation hierarchy. Finally, atstep 1703, a route from the object point and the destination Is producedby searching the route stored at step 1607. Consequently, the route fromthe starting point to destination is produced and Is output to theoutput means at step 1704.

According to the sixth embodiment, since a migration point is decided inthe forward migration point memory 1423 and backward migration pointmemory 1424 in advance, when a route changes from a hierarchy to otherhierarchy, the route can migrate between both the hierarchies via themigration point. The migration operation is carried out not only betweenneighboring two hierarchies but also between two hierarchies which areseparated with each other. Consequently, it is not necessary to changean Investigation hierarchy from a lower hierarchy to an upper hierarchystep by step as shown in fifth embodiment. Thus, a retrieval speed of aroute is further improved.

Moreover, the arrival range of connecting points stored with respect toeach point on each hierarchies is stored in the arrival range datamemory 1425. Therefore, efficient retrieval is carried out byinvestigating the object point on the basis of the arrival range, andhence the retrieval speed is further improved.

In the sixth embodiment, the range stored in the arrival range datamemory 1425 is represented by a circle which has a center of thereference point P as shown in FIG. 15, but the shape of the arrivalrange is not limited to the circle. Furthermore, for example, thearrival range may be determined by the number of connecting point withrespect to a reference point. The numbers of the reference point andobject point, in the sixth embodiment, is one or more. Since themigration point is classified Lo the forward migration point andbackward migration point and is stored in the respective memories, theclassification can correspond to the road of one-way traffic. If theone-way traffic is not considered, the classification to the forwardmigration point and backward migration point is not needed. In a searchoperation of a route from the destination to the starting point in viewof the one-way traffic, the road of one-way traffic can be passed toreverse direction by attaching a suitable identifier to the data of apoint representing the one way traffic.

In the sixth embodiment, when a detailed search of a lane is not needed,the detailed route search means 1402 and the road network memory 1422can be omitted.

The entire embodiments 1-6 as mentioned above will be able toaccommodate to a railway network. In the railway network, an optimumroute is derived on the basis of connection relation between stations,the minimum travel time or train fair.

Although the present Invention has been described in terms of thepresently preferred embodiments, It is to be understood that suchdisclosure is not to be interpreted as limiting. Various alterations andmodifications will no doubt become apparent to those skilled in the artafter having read the above disclosure. Accordingly, it is intended thatthe appended claims be interpreted as covering all alterations andmodifications as fall within the true spirit and scope of the Invention.

What is claimed is:
 1. A route selection method comprising the stepsof:defining, in advance, a connection network that includes a pluralityof points representing points on a map between which a person maytravel; storing, in advance in a memory, various combinations of pairsof said points, wherein each pair of points includes a first pointrepresenting an arbitrary starting point on said map, a second pointrepresenting an arbitrary destination point on said map, and at leastone transit point, if said transit point exists, said transit pointcorresponding to one of said plurality of points in said connectionnetwork that is located between said first point and said second pointin that pair of points and through which a person must travel inprogressing from said first point to said second point in that pair ofpoints; selecting any two points from said plurality of points in saidconnection network; searching said memory for a first pair of pointscorresponding to said selected two points and retrieving a first transitpoint associated with said first pair of points if said first transitpoint exists; searching said memory repeatedly for additional pairs ofpoints stored therein and retrieving transit points associated with eachadditional pair of points retrieved, wherein a first point in each ofsaid additional pairs of points corresponds to one of said selected twopoints and a second point in each of said additional pairs of pointscorresponds to a transit point retrieved in a preceding searchingoperation, if present, until a pair of points having no transit pointassociated therewith is located; and determining a route between saidtwo selected points by combining said two selected points with all ofsaid transit points retrieved during said searching and retrievingoperations.
 2. A route selection method comprising the stepsof:defining, in advance, a connection network that includes a pluralityof points representing points on a map between which a person maytravel, said plurality of points being subdivided into a plurality minorpoints and a plurality route store points; storing, in advance in aroute store memory, various combinations of pairs of said route storepoints, and storing at least one transit point associated with each pairof said route store points, if said transit point exists, wherein saidtransit point associated with a pair of route store points correspondsto one of said plurality of points in said connection network that islocated between a first route store point and a second route store pointin that pair of route store points through which a person must travel inprogressing from said first route store point to said second route storepoint in that pair of route store points; selecting any two points fromsaid plurality of points in said connection network, wherein one of saidselected two point corresponds to a starting point and another of saidselected two points corresponds to a destination point to which a userdesires to travel; determining if said selected two points correspondsto any of said route store points stored in said route store memory;retrieving from said route store memory a first route store pointproximate to said starting point, and determining a first route fromsaid starting point to said first route store point if said startingpoint does not correspond to any of said route store points; retrievingfrom said route store memory a second route store point proximate tosaid destination point, and determining a second route from saiddestination point to said second route store point if said destinationpoint does not correspond to any of said route store points; searchingsaid route store memory for a first pair of route store pointscorresponding to said first and said second route store points andretrieving a first transit point associated with said first pair ofpoints, if said first transit point exists; searching said route storememory repeatedly for additional pairs of route stores points storedtherein and retrieving a transit point associated with each additionalpair of route store points retrieved, wherein a first route store pointin each of said additional pairs of route store points corresponds toone of said first and said second route store points and a second routestore point in each of said additional pairs of route store pointscorresponds a transit point retrieved in a preceding searchingoperation, if present, until a pair of route store points having notransit point associated therewith is located; determining a searchedroute between said first and said second route store points by combiningsaid first and said second route store points with all of said transitpoints retrieved during said searching and retrieving operations; anddetermining a complete route between said starting point and saiddestination point by combining said first route, said second route andsaid searched route.
 3. A route selection method comprising the stepsof:defining, in advance, a connection network that includes a pluralityof points representing points on a map between which a person maytravel, said plurality of points being subdivided into a plurality minorpoints and a plurality route store points; storing, in advance in aroute store memory, various combinations of pairs of said route storepoints, and storing at least one transit point associated with each pairof route store points, if said transit point exists, wherein saidtransit point associated with a pair of route store points correspondsto one of said plurality of points in said connection network that islocated between a first route store point and a second route store pointin that pair of route store points through which a person must travel inprogressing from said first route store point to said second route storepoint in that pair of route store points; selecting any two points fromsaid plurality of points in said connection network, wherein one of saidselected two points corresponds to a starting point and another of saidselected two points corresponds to a destination point to which a userdesires to travel; determining if either of said selected two pointscorresponds to any one of said route store points; retrieving from saidroute store memory a plurality of first route store points proximate tosaid starting point, and determining a plurality of first routes fromsaid starting point to said plurality of first route store points, ifsaid starting point does not correspond to any one of said route storepoints; retrieving from said route store memory a plurality of secondroute store points proximate to said destination point, and determininga plurality of second routes from said destination point to saidplurality of second route store points if said destination point doesnot correspond to any of said route store points; conducting searchingoperations of said route store memory to determine a plurality ofcomplete routes between said starting point and said destination point,each searching operation including the steps of:searching said routestore memory for a pair of route store points that includes a firstroute store point from said plurality of first route store points and asecond route store point from said plurality of second route storepoints and retrieving a transit point associated with said pair of routestore points, if said transit point exists; searching said route storememory repeatedly for additional pairs of route stores points storedtherein and retrieving transit points associated therewith, wherein afirst route store point in said additional pairs of route store pointscorresponds to one of said first route store point and said second routestore point and a second route store point in said additional pairs ofroute store points corresponds a transit point retrieved in a precedingsearching operation, if present, said repeated searching continuinguntil a pair of route store points having no transit point associatedtherewith is located; determining a searched route between said firstand said second route store points by combining said first and saidsecond route store points with all of said transit points retrievedduring said searching and retrieving operations; and determining acomplete route between said starting point and said destination point bycombining said first route, said second route and said searched routeassociated with one another.
 4. A route selection method as defined inclaim 3, further comprising the steps of:selecting a predeterminednumber of said plurality of complete routes between said starting pointand said destination point; and outputting said predetermined number ofselected routes.
 5. A route selection method comprising the steps of:(a)defining, in advance, a connection network having a hierarchy structureand a plurality of points representing points on a map between which aperson may travel, wherein said hierarchy structure includes a pluralityof hierarchies from a lowest hierarchy to a highest hierarchy and saidplurality of points are associated with at least one of said pluralityof hierarchies, and wherein for each hierarchy there exists a pluralityof transition points representing a connection points betweenhierarchies; (b) storing, in a route memory in advance, datarepresenting said plurality of points and data representing apredetermined number of complete routes between a predetermined numberpoints located in a same hierarchy; (c) selecting two points from saidplurality of points in said connection network and stored in said routememory, said two points corresponding to a starting point and adestination point; (d) defining a first reference point as said startingpoint and a first object point as said destination point; (e) conductinga first searching operation of said route memory for a complete route ina first hierarchy between said first reference point and said firstobject point; (f) changing a hierarchy in which a route is searched forto a hierarchy above said first hierarchy if no complete route is foundduring said searching operation of said first hierarchy; (g) retrievinga first transition point located in said first hierarchy proximate tosaid first reference point and retrieving a first complete route betweensaid first reference point and said first transition point, if saidfirst reference point is not one of said plurality of transition pointsbetween said first hierarchy and said hierarchy above said firsthierarchy; (h) retrieving a second transition point located in saidfirst hierarchy proximate to said first object point and retrieving asecond complete route between said first object point and said secondtransition point, if said first object point is not one of saidplurality of transition points between said first hierarchy and saidhierarchy above said first hierarchy; (i) conducting a second searchingoperation of said route memory for a complete route in said hierarchyabove said first hierarchy between said first transition point and saidsecond transition point; (j) repeating steps (f)-(i) until a completeroute is found, wherein each time steps (f)-(i) are carried out, saidfirst hierarchy in which a route is searched for is incremented to anext higher hierarchy, said first transition point becomes said firstreference point and said second transition point becomes said firstobject point; and (k) determining a final complete route between saidstarting point and said destination point by combining all of said firstroutes, all of said second routes and said complete route.
 6. A routeselection method comprising the steps of:(a) defining, in advance, aconnection network having a hierarchy structure and a plurality ofpoints representing points on a map between which a person may travel,wherein said hierarchy structure includes a plurality of hierarchiesfrom a lowest hierarchy to a highest hierarchy and said plurality ofpoints are associated with at least one of said plurality ofhierarchies, and wherein for each hierarchy there exists a plurality ofmigration points representing connection points between hierarchies; (b)storing, in a memory in advance, data representing said plurality ofpoints, data representing said migration points, data representingdistance ranges associated with each of said migration points, and datarepresenting a predetermined number of complete routes between pointslocated in a same hierarchy, said points located in said same hierarchyincluding said points associated with that hierarchy and migrationpoints associated with that hierarchy; (c) selecting two points fromsaid plurality of points in said connection network stored in saidmemory, said two points corresponding to a starting point and adestination point; (d) retrieving a first group of said migration pointsassociated with said starting point, said first group of migrationpoints including migration points associated with each hierarchy in saidplurality of hierarchies, a first group of routes from said startingpoint to said first group of migration points, a second group ofmigration points associated with said destination point, said secondgroup of migration points including migration points associated witheach hierarchy in said plurality of hierarchies, and a second group ofroutes from said destination point to said second group of migrationpoint; (e) determining whether any of said second group of migrationpoints in a first hierarchy are within said distance ranges associatedwith said first group of migration points in said first hierarchy, andif not, repeating said determining step with respect to a next higherhierarchy until it is determined that at least one migration point fromsaid second group of migration points is within a distance range of atleast one migration point from said first group of migration points andretrieving all routes associated with said at least one migration pointfrom said first group of migration points; (f) determining whether saidat least one migration point from said second group of migration pointsis included in any one of said routes associated with said at least onemigration point from said first group of migration points; and (g)obtaining a complete route from said starting point to said destinationpoint if at least one migration point from said second group ofmigration points is included in any one of said routes associated withsaid at least one migration point from said first group of migrationpoints, said complete route being obtained by connecting a first routefrom said starting point to said at least of one migration point fromsaid first group of migration points, a second route from saiddestination point to said at least of one migration point from saidsecond group of migration points, and a third route that includes saidat least one migration point from said first group of migration pointsand said at least one migration point from said second group ofmigration points determined in step (f).
 7. A route selection methodaccording to claim 6, further comprising the step of repeating steps(e)-(g) using a still higher hierarchy in said determining operation ofstep (e), if at least one migration point from said second group ofmigration points is not included in any one of said routes associatedwith said at least one migration point from said first group ofmigration points.
 8. A route selection method according to claim 6,wherein, if a plurality of routes exist after completing steps (e) and(f), determining which of said plurality of route to use in saidobtaining step based on characteristic data associated with said routes.9. A route selection method according to claim 8, wherein saidcharacteristic data includes at least one of distance data, travel time,and traffic congestion.
 10. A route selection apparatus that establishesa complete route between two points on a connection network thatincludes a plurality of points representing points on a map betweenwhich a person may travel, said apparatus comprising:memory means forstoring various combinations of pairs of said points in a memory,wherein a first point in each pair of points represents an arbitrarystarting point on said map and a second point in each pair of pointsrepresents an arbitrary destination point on said map, and, storing onlyone transit point associated with each pair of points, if said transitpoint exists, said transit point associated with a pair of said pointscorresponds to one of said plurality of points in said connectionnetwork that is located between said first point and said second pointthat pair of points and through which a person must travel inprogressing from said first point to said second point in that pair ofpoints; input means for selecting any two points from said plurality ofpoints in said connection network; means for searching said memory for afirst pair of points corresponding to said selected two points andretrieving a first transit point associated with said first pair ofpoints if said first transit point exists; means for repeatedlysearching said memory for additional pairs of points stored therein andretrieving transit points associated with each additional pair of pointsretrieved, wherein a first point in said additional pairs of pointscorresponds to one of said selected two points and a second point insaid additional pairs of points corresponds to a transit point retrievedin a preceding searching operation, if present, until a pair of pointshaving no transit point associated therewith is located; and means fordetermining said complete route between said two selected points bycombining said two selected points with all of said transit pointsretrieved during said searching and retrieving operations.
 11. A routeselection apparatus that establishes a complete route between two pointson a connection network that includes a plurality of points representingpoints on a map between which a person may travel, said plurality ofpoints being subdivided into a plurality minor points and a pluralityroute store points, said apparatus comprising:route store memory meansfor storing various combinations of pairs of said route store points,and storing at least one transit point associated with each pair of saidroute store points, if said transit point exists, wherein said transitpoint associated with a pair of said route store points corresponds toone of said plurality of points in said connection network that islocated between a first route store point and a second route store pointin that pair of route store points through which a person must travel inprogressing from said first route store point to said second route storepoint in that pair of route store points; input means for selecting anytwo points from said plurality of points in said connection network,wherein one of said selected two points corresponds to a starting pointand another of said selected two points corresponds to a destinationpoint to which a user desires to travel; means for determining if eitherof said selected two points corresponds to any of said route storepoints stored in said route store memory; means for retrieving from saidroute store memory a first route store point proximate to said startingpoint and for determining a first route from said starting point to saidfirst route store point if said starting point does not correspond toany of said route store points; means for retrieving from said routestore memory a second route store point proximate to said destinationpoint and for determining a second route from said destination point tosaid second route store point if said destination point does notcorrespond to any of said route store points; means for searching saidmemory for a first pair of route store points corresponding to saidfirst and said second route store points and retrieving a first transitpoint associated with said first pair of points, if said first transitpoint exists; means for repeatedly searching said memory for additionalpairs of route stores points stored therein and retrieving a transitpoint associated with each additional pair of route store pointsretrieved, wherein a first route store point in said additional pairs ofroute store points corresponds to one of said first and said secondroute store points and a second route store point in said additionalpairs of route store points corresponds a transit point retrieved in apreceding searching operation, if present, said repeated searchingcontinuing until a pair of route store points having no transit pointassociated therewith is located; means for obtaining a searched routebetween said first and said second route store points by combining saidfirst and said second route store points with all of said transit pointsretrieved during said searching and retrieving operations; and means forobtaining said complete route between said starting point and saiddestination point by combining said first route, said second route andsaid searched route.
 12. A route selection apparatus for establishing aroute between two points in a connection network that includes aplurality of points representing points on a map between which a personmay travel, said plurality of points being subdivided into a pluralityminor points and a plurality route store points, said apparatuscomprising:route store memory for storing various combinations of pairsof said route store points, and storing at least one transit pointassociated with each pair of route store points, if said transit pointexists, wherein said transit point associated with a pair of said routestore points corresponds to one of said plurality of points in saidconnection network that is located between a first route store point anda second route store point in that pair of route store points throughwhich a person must travel in progressing from said first route storepoint to said second route store points that pair of route store points;input means for selecting any two points from said plurality of pointsin said connection network, wherein one of said selected two pointscorresponds to a starting point and another of said selected two pointscorresponds to a destination point to which a user desires to travel;means for determining if either of said selected two points correspondsto any one of said route store points; means for retrieving from saidroute store memory a plurality of first route store points proximate tosaid starting point and for determining a plurality of first routes fromsaid starting point to said plurality of first route store points, ifsaid starting point does not correspond to any one of said route storepoints; means for retrieving from said route store memory a plurality ofsecond route store points proximate to said destination point and fordetermining a plurality of second routes from said destination point tosaid plurality of second route store points if said destination pointdoes not correspond to any of said route store points; wherein searchingoperations of said route store memory are conducted to determine aplurality of complete routes between said starting point and saiddestination point, said searching operations being conducted by:meansfor searching said route store memory for a pair of route store pointsthat includes a first route store point from said plurality of firstroute store points and a second route store point from said plurality ofsecond route store points and retrieving a transit point associated withsaid pair of route store points, if said transit point exists; means forrepeatedly searching said route store memory for additional pairs ofroute stores points stored therein and retrieving a transit pointassociated with each additional pair of route store points retrieved,wherein a first route store point in said additional pairs of routestore points corresponds to one of said first route store point and saidsecond route store point and a second route store point in saidadditional pairs of route store points corresponds a transit pointretrieved in a preceding searching operation, if present, and whereinsaid means for repeatedly searching continues said repeated searchingoperation until a pair of route store points having no transit pointassociated therewith is located; means for obtaining a searched routebetween said first and said second route store points by combining saidfirst and said second route store points with all of said transit pointsretrieved during said searching and retrieving operations; and means forobtaining a complete route between said starting point and saiddestination point by combining said first route, said second route andsaid searched route associated with one another.
 13. A route selectionapparatus as defined in claim 12, further comprising:means for selectinga predetermined number of said plurality of complete routes between saidstarting point and said destination point; and means for outputting saidpredetermined number of selected routes.
 14. A route selection apparatusfor obtaining a complete route between two points on a connectionnetwork having a hierarchy structure and a plurality of pointsrepresenting points on a map between which a person may travel, whereinsaid hierarchy structure includes a plurality of hierarchies from alowest hierarchy to a highest hierarchy and said plurality of points areassociated with at least one of said plurality of hierarchies, andwherein for each hierarchy there exists a plurality of transition pointsrepresenting a connection points between hierarchies, said apparatuscomprising:route memory for storing data representing said plurality ofpoints and data representing a predetermined number of complete routesbetween a predetermined number of points located in a same hierarchy;input means for selecting two points from said plurality of points insaid connection network and stored in said route memory, said two pointscorresponding to a starting point and a destination point; means fordefining a first reference point as said starting point and a firstobject point as said destination point; first searching means forconducting a first searching operation of said route memory for acomplete route in a first hierarchy between said first reference pointand said first object point; changing means for changing a hierarchy inwhich a route is searched for to a hierarchy above said first hierarchyif no complete route is found during said searching operation of saidfirst hierarchy; retrieving means for retrieving from said route memorya first transition point located in said first hierarchy proximate tosaid first reference point and retrieving a first complete route betweensaid first reference point and said first transition point, if saidfirst reference point is not one of said plurality of transition pointsbetween said first hierarchy and said hierarchy above said firsthierarchy, and for retrieving a second transition point located in saidfirst hierarchy proximate to said first object point and retrieving asecond complete route between said first object point and said secondtransition point, if said first object point is not one of saidplurality of transition points between said first hierarchy and saidhierarchy above said first hierarchy; wherein said searching meansconducts a second searching operation of said route memory for acomplete route in said hierarchy above said first hierarchy between saidfirst transition point and said second transition point; means foroperating said changing means, said retrieving means and said searchingmeans until a complete route is found, wherein each time said changingmeans, said retrieving means and said searching means are operated, saidfirst hierarchy in which a route is searched for is incremented to anext higher hierarchy, said first transition point becomes said firstreference point and said second transition point becomes said firstobject point; and means for obtaining said complete route between saidstarting point and said destination point by combining all of said firstroutes, all of said second routes and said complete route.
 15. A routeselection apparatus for obtaining a complete route between two points ona connection network having a hierarchy structure and a plurality ofpoints representing points on a map between which a person may travel,wherein said hierarchy structure includes a plurality of hierarchiesfrom a lowest hierarchy to a highest hierarchy and said plurality ofpoints are associated with at least one of said plurality ofhierarchies, and wherein for each hierarchy there exists a plurality ofmigration points representing connection points between hierarchies,said apparatus comprising:memory means for storing, in a memory inadvance, data representing said plurality of points, data representingsaid migration points, data representing distance ranges associated witheach of said migration points, and data representing a predeterminednumber of complete routes between points located in a same hierarchy,said points located in said same hierarchy including said pointsassociated with that hierarchies and migration points associated withthat hierarchy; input means for selecting two points from said pluralityof points in said connection network stored in said memory, said twopoints corresponding to a starting point and a destination point; meansfor retrieving a first group of said migration points associated withsaid starting point, said first group of migration points includingmigration points associated with each hierarchy in said plurality ofhierarchies, a first group of routes from said starting point to saidfirst group of migration points, a second group of migration pointsassociated with said destination point, said second group of migrationpoints including migration points associated with each hierarchy in saidplurality of hierarchies, and a second group of routes from saiddestination point to said second group of migration point; determiningmeans for determining whether any of said second group of migrationpoints in a first hierarchy are within said distance ranges associatedwith said first group of migration points in said first hierarchy, andif not, for repeating said determining operation with respect to a nexthigher hierarchy until it is determined that at least one migrationpoint from said second group of migration points is within a distancerange of at least one migration point from said first group of migrationpoints and retrieving all routes associated with said at least onemigration point from said first group of migration points, and fordetermining whether said at least one migration point from said secondgroup of migration points is included in any one of said routesassociated with said at least one migration point from said first groupof migration points; and obtaining means for obtaining a complete routefrom said starting point to said destination point if at least onemigration point from said second group of migration points is includedin any one of said routes associated with said at least one migrationpoint from said first group of migration points, said complete routebeing obtained by connecting a first route from said starting point tosaid at least of one migration point from said first group of migrationpoints, a second route from said destination point to said at least ofone migration point from said second group of migration points, and athird route that includes said at least one migration point from saidfirst group of migration points and said at least one migration pointfrom said second group of migration points determined by saiddetermining means.
 16. A route selection apparatus according to claim15, further comprising means for operating said determining means andsaid obtaining means, wherein each time said determining means and saidobtaining means are operated a still higher hierarchy is used in saiddetermining operation, if at least one migration point from said secondgroup of migration points is not included in any one of said routesassociated with said at least one migration point from said first groupof migration points.
 17. A route selection apparatus according to claim15, further comprising means, if a plurality of routes exist afteroperating said determining means, for determining which of saidplurality of route to be used said obtaining means based oncharacteristic data associated with said routes.
 18. A route selectionapparatus according to claim 17, wherein said characteristic dataincludes at least one of distance data, travel time, and trafficcongestion.